This isn't really about derivatives. It's simply the idea that not every symbol is an independent variable. Some of them are defined in terms of other symbols, and you can use those definitions in everything you do.
I don't know how/if any other program handles this. I just assumed any CAS would do it, since it's so basic to the way humans do mathematics. But maybe it's harder than I thought. Peter -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/76da646f-f921-4291-b66b-9c6283a3f0a6%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
